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Vanishing Tertiary Genetic Heritage in the
East Mediterranean, Liquidamber Orientalis
Mill.
By: M. Ozturk1,
C. R. Parks2, F. Coskun3, G. Gork4, O. Secmen1
Very few people comprehend the importance and
meaning of biodiversity; a common buzzword of these days. Habitat loss and
genetic erosion are mainly responsible for the loss of our biodiversity leading
towards species extinction. Most of the interpretations make a mention of this
term as species diversity, including a plethora of living organisms and their
habitats. However, ecologically it is an attribute of three other levels of
biological organization namely; genetic diversity, community diversity and
landscape diversity. In any case whenever we think of the quantitative side of
this theme we start with number of species. Turkey with a population of 67
million inhabitants embodies more than 9000 taxa of pteridophytes and
spermatophytes, including over 3000 endemics. This makes it one of the
important plant diversity hotspots in the Mediterranean basin as well as
Europe. The medicinal, agricultural and consumptive use values of this
diversity together with their involvement in biogeochemical cycles, prevention
of soil erosion, ecotourism, and regulation of climate provide the very basis
of a countriy’s socio- economic development. We are losing 24-100 species a day
due to habitat loss, introduction of alien species, pollution and over
exploitation. The species extinction is proceeding at such a high rate that
coming generations can face serious consequences.
Liquidambar orientalis
an east Mediterranean element with a boreal tertiary origin is one among such
species facing a threat of extinction.
The oriental
sweetgum, Liquidambar orientalis Mill. is a tertiary period
relict endemic taxon of the East Mediterranean, distributed naturally only in
the South and West Anatolian parts of Turkey, mainly on sandy soils, with a
high pH. The monoecious trees form dense forests confined to floodplains,
valleys and along streams and in a few dry habitats. In Turkish it is called
“gunluk” due to the fragrance of the trees or “sigla” because of the gum like
exudates, which has been used for more than seven hundred years as an all
purpose drug, in particular as the most effective cure for stomach ulcers.
The name
Liquidambar is said to have been given by Monardes in the 16th century as
the name of the resin obtained in Mexico from the American species, now
L. styraciflua.
The balsamic
resin is collected from March till September every year from the trunks of
about 10 years old trees with a girth of 15 cm. In Turkish it is called gunluk
due to the fragrance of the trees or sigla because of the gum like exudate
which develops in response to injury, being thus more a pathological than
physiological response. The balsam containsα-pinene, β-pinene, myrcene,
camphene, limonene, 1,8-cineol, p-cymene, terpinolene, linaool, 4-terpinenol,
α-terpineol, dihydrocoumarone, cinnamic aldehyde, trans-methyl cinnamate,
1-benzoyl-3-phenylpropyne, β-phenylpropionic acid, benzoic acid, palmitic acid,
and linoleic acid (12,37). The residual bark left after the extraction has been
named as cortex thymiamatis, cortex thuris and storax bark. The resin is soft,
viscid semi-liquid, grayish to grayish brown in color, semi-opaque, with a
honey like consistence, balsamic odor, and pungent, aromatic, burning taste. It
has been confined with a similar product obtained from a typical Mediterranean
macchia element Styrax officinalis in earlier times. Later on term
styrax was used for the resin of Liquidambar and storax for that of
Styrax officinalis.
The early
history of the resin is a little mixed up, but it surely goes back to
Theophrastus and Herodotus (Hus 1949). An authenticated record clearly gives
its use somewhere in 629 A. D., which refers to Chinese sources as well as to
the name zygia (12,26). In the 7th century Su Kung has written about the drug
named as su ho hiang which is a kind of styrax coming from western Asia ( 38).
Chinese have mentioned about Liquidambar exudate as an excrement of
lions as well as a symbol of tranquility and perfume to expel evil spirits. The
wood of Liquidambar has been used to make tea chests in China. It also
has been used to make idols due to the waving of branches and fluttering of
leaves in the wind which led Chinese to a belief that this tree is inhabited by
spirits. Due to its incense characteristics, it is used even now in mosques and
churches in several countries. According to Kang Mu ( 26) styrax was considered
as a cure-all drug in the Chinese medicine, to treat ulcers, hemorrhage,
toothache, scales, swellings, some of the cancerous outgrowths, improvement of
circulation and healing of wounds as well as cuts. A similar use has been put
forth for root and leaf preparations. Other medical sources of 16th century
however, have not been referring to all these cures. Styrax of course has
served as an important drug for seven hundred years. It has been used as an
expectorant in asthma, bronchitis, and lung infections, in fumigatories,
incenses, perfumes and skin diseases. The bark is said to have been used to
cure colds, diabetes, dysentry, cholera and dropsy (38). Chinese literature
also cites the preparations from the fruits to cure back-aches, spasms, eye
clearing and prevention of plague. Out of this large list of cures the only one
left behind today is treatment of ulcers under the name storaxol (26) and its
use in compound tincture benzoin. It is also used in adhesives and tobacco
industry. The resin which develops in response to injury, more a pathological
response than physiological one, is consumed directly even now in Turkey to
treat ulcer. It is sold at the market in Marmaris area. One teaspoon of the
resin is mixed up with one teaspoon of honey and taken directly with empty
stomach daily in the mornings for 10 days. The residue left after resin
pressing is used as an incense in mosques. Lately the production of the resin
in Turkey has however, diminished tremendously from 180 to 1 ton due to its
less use and destruction of these relict forests.
Threats to extinction:
The forests of L. orientalis
have been severely destroyed during the last 200 years. This
disappearance has started the chain of events leading to an extinction of many
other species. Unfortunately, the landscape is
becoming increasingly fragmented leading towards a loss of too many
species, which means a psychological and spiritual loss too. There is an urgent
need for sustained maintenance of these forests for scientific, utilitarian,
and ethical purposes. The fragrant aromatic balsamic resin appears to keep the
insects and fungi away from the healthy populations of oriental sweetgum. In
fact these forests have suffered much from the anthropogenic pressures than
insect attacks. Major factors involved in the destruction of this important
genetic heritage are cutting and felling for field openings and settlements.
This practice has continued for over 200 years. Earlier, Egyptian experts
living around Nile delta were despatched to this region during Ottoman Empire
to drain these swampy areas in view of their know-how in this field. During
last few decades the trees are first cut followed by planting fast growing
Eucalyptus globules, which dries up these areas. Latter plantations are
felled then and citrus orchards established. These orchards are maintained
whence they are taken over by land speculators for constructing summer
residential quarters, since a major part of these forests lies near to the
coast on the Aegean and Mediterranean Sea. In addition, use of these forests as
grazing grounds because of the rich herbaceous undercover as well as inflicting
injuries through deep and long cuts for the procurance of resin add to the
major destructive activity cited above. The trees used for the exudates
production live for 30 years but untouched trees live for more than 100 years.
Bark Pollution:
The bark of trees growing along roadsides was observed to be darker in colour
than those away from the highways. The thickness of bark of the trees in
unpolluted sites in the states of Antalya, Isparta, Denizli, Aydin and Datca
was recorded as 0.9 -1.1 cm and bark pH at these sites varied between
4.3–6.6, whereas thickness in medium polluted sites like Yatagan, Milas and
Marmaris in the state of Mugla was 1.3-1.4 cm and pH of the bark samples was
3.3-4.7. In the highly polluted samples collected from the trees alongside the
highway passing through Koycegiz bark thickness was 1.5 cm and pH varied
between 2.8-3.7. In the latter area very low epiphytic and ground plant cover
was observed in the forests along the highway. This can be attributed to the
pollution due to leaded gasoline originating from the heavy traffic.
Conclusions:
The area of this taxon has got reduced
from 7000 to 1657.80 ha during the
last 200 years. Major anthropogenic impacts involved in the decline of this
important genetic heritage are habitat destruction due to cutting and felling
for wood, followed by a change of the land use, grazing, resin extraction and
urban development pressures. The loss of this precious genetic resource
has been increasingly more in the recent past mainly due to degradation and
shrinking habitat and often their complete loss due to cutting, summer house
constructions, tourism and land acquisition for agricultural purposes. This
problem is acute in the Mediterranean, due to increasing chunk of area being
used for tourism. There is an urgent need
for its in situ conservation. Although some protected areas have been earmarked
but the preservation and restoration of these
open spaces is insufficient to maintain and rebuild biodiversity. There
is an urgent need for an international support as well for maintenance of this
area as an in situ conservation site as well as a world heritage site. This
will help us to re-establish biological
continuums in the L.orientalis distributional zone. In Europe national
and regional maps defining the networks of ecological corridors are expected to
be set up until 2005. Like Europe the ecological network is the backbone of the
biodiversity strategy for ecology and landscapes in the Mediterranean basin
too. But the countries bordering the Mediterranean are dragging their feet, as
is often the case where protection of biodiversity is concerned. The
species is shown as vulnerable (degree of threat) in the plants of Europe
threatened tree Project. There is an immediate need for a protection of the
forests of this plant species through in-situ conservation.
In situ conservation of special, vulnerable
ecosystems is essential. These include all habitats with emphasis on mountains,
wetlands and deserts. Many of their representative areas are now protected.
According to IUCN report these protected areas numbering 9800 cover
92,63,49,000 ha area of earth surface. Immense possibilities exist for in‑situ
conservation
L.orientalis.
Since it is a common property
resource, active involvement of local people in their management will always be
a pre‑requisite for their better management and conservation.
1M.
Ozturk and 0. Secmen,
Botany Department, Ege University, Bornova - Izmir,
Turkey
2C.R.Parks
Biology
Department, The University of North Carolina-Chapel Hill, N.C.,
USA
3F.
Coskun,
Biology Department, Balikesir University, Balıkesir,
Turkey
4G.
Gork,
Biology Department, Mugla University, Mugla,
Turkey |
